Simpson W A, Ofek I, Beachey E H
J Biol Chem. 1980 Jul 10;255(13):6092-7.
The ability of the fatty acid binding sites of serum albumin to bind lipoteichoic acid of Streptococcus pyogenes was investigated. Initial studies indicated that lipoteichoic acid, but not its deacylated deprivative, protected albumin from being denatured by heat (80C for 1 h) and changed its mobility in an electrical field. Albumin covalently linked to agarose beads bound radiolabeled lipoteichoic acid, and the bound [3H]lipoteichoic acid could be specifically eluted with unlabeled lipoteichoic acid or albumin but not with other proteins tested. After binding to albumins, the lipoteichoic acid also could be quantitatively eluted with 50% ethanol and various detergents but not with up to 1.0 M sodium chloride. Binding of lipoteichoic acid to albumin followed first order kinetics, reaching saturation at 12 h. Analysis of the binding data by a Scatchard plot indicated heterogeneity of the binding sites on the albumin molecule similar to that previously reported for fatty acids. The affinity of binding of lipoteichoic acid to albumin was found to be intermediate between that previously reported for octanoic and palmitic acids, respectively. Based on these findings, we prepared affinity columns of immobilized albumin and were able to separate biologically active lipoteichoic acid from heterogeneous extracts of S. pyogenes.
研究了血清白蛋白的脂肪酸结合位点与化脓性链球菌脂磷壁酸结合的能力。初步研究表明，脂磷壁酸而非其脱酰基衍生物能保护白蛋白免受热（80℃，1小时）变性，并改变其在电场中的迁移率。与琼脂糖珠共价连接的白蛋白结合放射性标记的脂磷壁酸，结合的[3H]脂磷壁酸可用未标记的脂磷壁酸或白蛋白特异性洗脱，但不能用所测试的其他蛋白质洗脱。与白蛋白结合后，脂磷壁酸也可用50%乙醇和各种去污剂定量洗脱，但不能用高达1.0M的氯化钠洗脱。脂磷壁酸与白蛋白的结合遵循一级动力学，在12小时达到饱和。通过Scatchard图分析结合数据表明，白蛋白分子上结合位点的异质性与先前报道的脂肪酸类似。发现脂磷壁酸与白蛋白结合的亲和力介于先前报道的辛酸和棕榈酸之间。基于这些发现，我们制备了固定化白蛋白亲和柱，并能够从化脓性链球菌的异质提取物中分离出生物活性脂磷壁酸。
